1. Field of the Invention
The present invention relates generally to robotic media storage library systems, and more specifically to a redundant system that includes a plurality of independent robots in the form of robotic pods.
2. Background of the Invention
The current enterprise class library system contains multiple independent robots for concurrently manipulating multiple media cartridges. The library system comprises an array of media storage cells and media cartridge players. A system of rails is used to guide robotic pods through al of the locations on the array.
The current enterprise class library has a few redundant features, such as redundant robots and the robot servo controllers. However, there are still many potential single points of failure in the robotics electrical components (i.e. main controller, interrupt controller, etc.). If a failure occurs in one of these components, it may make the unit non-operational. Currently, there is a customer demand for high availability (99.999% run time) on enterprise class tape automated libraries, which requires minimum system down time due to individual component failures.
Library systems with two or more redundant robots have been implemented in the marketplace. However, adding redundant robots increases the complexity of managing spare robots among different library sections. This problem is compounded when additional layers of redundancy are used to handle multiple system failures.
Therefore it would be desirable to have a method for providing seamless transition from failed robotics to backup robotics within a data storage library, without the need for user intervention.
The present invention provides a xe2x80x9chot sparexe2x80x9d method for facilitating the seamless transition from a failed robotic mechanism to backup unit. A spare robot is located inside a storage library on a section of rail (robotic track) from which it can be utilized on any rail layer in a multi-layer architecture. In one embodiment of the present invention, a motorized elevator assembly is used to transport the spare robot to the proper library level, which allows a single redundant robot to support multiple robots on multiple library rail levels. In another embodiment, a hot spare robot is used on each rail level and is utilized if needed on that particular level. In both embodiments, the spare robots are available for immediate backup without direct user intervention.